Extrahepatic autoimmune diseases in autoimmune hepatitis: Effect on mortality

BACKGROUND AND AIMS: Autoimmune hepatitis (AIH) is a chronic inflammatory liver disease associated with an increased prevalence of extrahepatic autoimmune diseases and an increased mortality compared with the general population. The contribution of extrahepatic autoimmune diseases to the increased mortality has not been clarified. Our aim was to determine the effect of extrahepatic autoimmune diseases on mortality in AIH patients. METHODS: This nationwide register‐based cohort study included all Danish patients diagnosed with AIH between 1995 and 2019. We examined the presence of extrahepatic autoimmune diseases and compared the mortality between AIH patients with and without extrahepatic autoimmune diseases. We adjusted our analysis for age, sex, calendar year of AIH diagnosis, cirrhosis, cancer, chronic obstructive pulmonary disease and ischaemic heart disease. RESULTS: We included 2479 AIH patients of whom 19.8% had one extrahepatic autoimmune disease and 3.3% had multiple. The adjusted 10‐year cumulative mortality was 27.2% (95% confidence interval [CI]: 25.2–29.4) for patients with extrahepatic autoimmune diseases and 21.6% (95% CI: 19.9–23.6) for patients without. The adjusted mortality hazard ratio was 1.30 (95% CI: 1.12–1.52) for AIH patients with versus without extrahepatic autoimmune diseases; it was 1.25 (95% CI: 1.06–1.48) for patients with one extrahepatic autoimmune disease and 1.54 (95% CI: 1.15–2.05) for those with more than one. CONCLUSIONS: Extrahepatic autoimmune diseases increased the mortality in patients with AIH. Patients with multiple extrahepatic autoimmune diseases had a higher mortality than patients with just one extrahepatic autoimmune disease.